[1.04] Dynamics of Interplanetary Dust: Modeling the Zodiacal Cloud

The most important dynamical features of the zodiacal cloud
are: (i) the dust bands associated with the major Hirayama
asteroid families, (ii) the circumsolar ring of asteroidal
dust particles in resonant lock with the Earth, (iii) the
offset of the center of symmetry of the cloud from the Sun,
the tilt of the cloud with respect to the ecliptic, and the
warp of the cloud, all produced by secular perturbations,
(iv) the radial gradient of the ecliptic polar brightness,
determined by the distribution of material at 1 AU.

The dust bands provide the clearest evidence that a
substantial and possibly dominant fraction of the cloud
originates from asteroids. However, the characteristic
diameter of these particle is probably several hundred
microns, and the migration of these particles towards the
inner Solar System due to Poynting-Robertson light drag and
their slow passage through secular resonances at the inner
edge of the asteroid belt results in large increases in
their eccentricities and inclinations. For this reason, it
may be difficult to distinguish clearly between asteroidal
and cometary particles in the inner Solar System on
dynamical grounds alone.

K.G. acknowledges support by the STIS IDT through NOAO by
NASA. This research is supported by NASA PG&G grant
NAG5-4531 and ADP grant NAG5-9280.